In 1892, U.S. President Benjamin Harrison designated a forest reserve in the San Gabriel Mountains to protect the watersheds supplying an expanding Los Angeles. Local developers and politicians supported the reserve, believing it would curtail fires set by sheepherders and campers that threatened agricultural and residential development in the foothills of the San Gabriels. Over the course of the early twentieth century, the U.S. Forest Service and the Los Angeles city and county fire departments advanced an aggressive policy of fire suppression in Los Angeles’s mountains and canyons. Growing scientific expertise and substantial firefighting infrastructure failed to contain the year-by-year increase in human-caused fires as developers, undeterred by increasing risk, expanded into foothill and coastal areas. Drawing upon regional newspapers, the papers of local conservationists, and city, county, state, and federal records, this presentation examines how fire management practices in Los Angeles came to prioritize total fire suppression over land use restrictions and prescribed burning in fire and flood-prone communities.